It has become common to print the design of the iris of an eye onto the surface of a contact lens so as to change the color of the eye of the user. One method of printing the design of an iris of an eye into a contact lens is to apply the print to the concave surface of a mold that is used to form the convex outer surface of the contact lens. When the polymer is subsequently applied to the mold and allowed to harden to form a lens, the contact lens will have the printing embedded into its convex surface. A print pad that is capable of printing such a design onto the convex surface of a mold for manufacturing a contact lens must be capable of deforming so as to contact the entire inner surface of the concave mold.
Existing print pads are made of a flexible polymer and have a spherical forward end. It has been found that the spherical forward end of existing pads will successfully apply print to the center of the concave mold, but cannot apply printing to the outer edges of the mold without causing distortion to the print applied to the center. Efforts to improve upon the spherical configuration of a print pad have resulted in print pads that do not linearly compress axially as force is applied to the concave mold, and therefore the pad does not print evenly around the outer circumference of the mold. Accordingly, there is a need for a print pad that can apply print evenly across the concave surface of a mold.